Volume rendering reconstructions of the anatomy of small aquatic beetles (Insecta: Coleoptera) scanned with the Skyscan 1172 high resolution micro-CT J. Alba-Tercedor & C.E. Sáinz-Cantero Caparrós Department of Zoology. Faculty of Sciences. University of Granada. 18071-Granada. Spain. jalba@ugr.es Aims Many things have changed since we started to use the high resolution Skyscan 1172 micro tomography system, for the study of anatomical details of aquatic insects (Alba-Tercedor & Sáinz-Cantero, 2010). First it all we improved our skills and experience, and secondly the constant improvements implemented to the software and very especially the development of the volume rendering CTVox program helped us to improve extraordinary the final results. Now it is possible to obtain good quality images, comparable to these obtained with the SEM, but with all the advantages that the microtomography technique has. We decided to present this paper to share with other users our experiences and tricks, when scanning very small insects. Method Animals from collection, already preserved in 70% ethanol, were dehydrated by the standard procedure of introducing the specimens for 2 hours in each of a series of ethanol solutions (with increasing percentage of concentrations: 80, 90 and 100%, respectively). The animals were dried before to scan them. We tested two methods to dry up the animals: a) by a standard critical point and b) by submerging the specimens for 2 hours in Hexamethyldisilazane and air drying overnight (Alba-Tercedor & Sánchez Tocino (2011 & 2012). To fix the specimens on the sample holder we essayed with plasticiline, or gluing them to different filaments (entomological minutien pins, thin filaments of copper from an electrical wires, regular pins, and fishing lines with a thickness appropriate for the specimen’s diameter (Fig. 1). Animals were scanned with no filter, with the micro-CT SkyScan 1172 C, by conducting oversized scans. We present here results obtained with two different representatives of little aquatic beetle insects: a female of the family Dryopidae (Dryops sp. Length ca. 4.5 mm. Scanned at Source Voltage: 71 KV, Source Current:80 μA, image pixel size: 12.7 μm), and a male of the family Hydraenidae (Hydraena exasperata Orchymont, 1935. Length ca. 2.2 mm. Scanned at Source Voltage: 57 KV, Source Current:100 μA, image pixel size: 1.8 μm).